Increased Graft Occlusion or String Sign in Composite Arterial Grafting for Mildly Stenosed Target Vessels

doi:10.1016/j.athoracsur.2009.11.053

The Annals of Thoracic Surgery

Volume 89, Issue 3, March 2010, Pages 683-687

https://doi.org/10.1016/j.athoracsur.2009.11.053 Get rights and content

Background

Composite grafting is a useful technique that avoids the need for aortic manipulation and enables a wide range of target vessels to be revascularized, effectively using the limited arterial grafts available. However, it has not been clarified whether composite grafting can achieve angiographic outcomes equivalent to those obtained with individual grafting for specific target vessels.

Methods

We retrospectively reviewed 830 distal arterial graft anastomoses in 256 patients who underwent off-pump coronary artery bypass surgery and also underwent 1-year follow-up coronary angiograms. Four hundred and ten anastomoses using a composite grafting technique were compared with 420 anastomoses using individual grafting.

Results

In target vessels with mild stenosis, the incidence of graft occlusion or string sign was significantly higher in composite internal thoracic arteries (ITA) than in individual ITA grafts (composite 20.3% versus individual 7.3%; p = 0.018) and showed a higher tendency in composite radial arteries (RA) than in individual RA grafts (59.3% versus 36.4%, p = 0.09). In contrast, the incidence was similar between composite and individual ITA grafts (5.7% versus 3.3%, p = 0.278) and composite and individual RA grafts (11.5% versus 29.6%, p = 0.297) in target vessels with severe stenosis.

Conclusions

The angiographic outcomes of composite grafts were closely related to the severity of stenosis of the target coronary artery. In target vessels with mild stenosis, composite grafting resulted in a higher incidence of graft occlusion or string sign than individual grafting did.

Section snippets

Study Design

This was a retrospective cohort study to verify the hypothesis that angiographic outcomes of composite grafts were inferior to those of individual grafts in target vessels with mild stenosis. One-year angiographic outcomes of arterial grafts were reviewed, and incidence of graft occlusion or string sign was compared between composite and individual grafts according to the severity of stenosis of the target coronary artery. Moreover, multivariate analysis was performed to identify the

Results

Incidence of graft occlusion or string sign was compared between composite grafts and individual grafts according to graft material, location of target coronary artery, and stenosis of target coronary artery (Table 3). There were significant differences between composite and individual grafts in ITA grafts and in the presence of mild stenosis of target coronary artery.

Incidence of graft occlusion or string sign in ITA and RA graft according to severity of target coronary artery is shown in

Comparison of Composite and Individual Grafting

The present study revealed that the angiographic outcomes of composite grafts were closely related to the severity of stenosis of the target coronary artery. Several previous studies reported that the patency rate of composite grafts was equal to that of individual grafts [1, 2, 3]. However, none of them examined the patency rate in relation to stenosis of the target coronary artery. Suboptimum angiographic results of composited grafting for mildly stenosed target vessels have been reported by

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There are more references available in the full text version of this article.

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Citation Excerpt :
The authors highlighted the heterogeneous and contradictory results reported and concluded that the evidence suggests that the site of the proximal anastomosis has little or no effect on RA graft patency. The only two studies that evaluated the angiographic results of RA grafts based on the proximal anastomotic site and the severity of the stenosis of the target vessel both reported that ITA-anastomosed grafts have substantially higher failure rates in case of nonocclusive coronary stenosis [36, 37]. Although the published evidence is far from conclusive, it is important to note that the finding of a better patency rate for RA grafts anastomosed to the aorta has been replicated by at least three studies, whereas no author has reported better patency for ITA-based grafts.
The radial artery has been used for coronary artery bypass surgery for more than 25 years. The recent confirmation of the clinical benefits associated with the use of the artery is likely to drive a new interest toward this conduit in the next few years.
A group of surgeons with extensive experience in the systematic use of the radial artery summarize here the key technical aspects of the use of the conduit for coronary bypass operations.
Preoperative evaluation of the ulnar collateral circulation and attention to the characteristics of the target vessel are keys for the successful use of the radial artery. Open or endoscopic harvesting can be used, preferentially with the aid of the harmonic scalpel. The use of vasodilatory and antispastic protocols is probably important but poorly supported by the current evidence. The radial artery can be used for multiple grafting strategies with a variable degree of technical complexity.
With attention to few technical key points, the radial artery is a versatile conduit that can be easily introduced in the everyday practice of coronary artery bypass surgery.
Hemodynamics of the string phenomenon in the internal thoracic artery grafted to the left anterior descending artery with moderate stenosis
2016, Journal of Biomechanics
Citation Excerpt :
Thus the string phenomenon in ITA is an intermediate process between shrinking and loss of function or occlusion (Kitamura et al., 1992). Most researchers hold the view that the string phenomenon is caused by the competitive flow when the stenosis in the native coronary artery is not serious (Geha and Baue, 1979; Hashimoto et al., 1996; Kolozsvari et al., 2012; Manabe et al., 2010; Siebenmann et al., 1993). According to Berger et al. (2004) the degree of stenosis is the most important factor affecting the incidence of ITA graft occlusion; the incidence of ITA graft occlusion is up to 79%, when the native coronary stenosis degree is less than 50%.
The internal thoracic artery is the choice of graft for coronary artery bypass grafting due to the excellent long-term patency. However internal thoracic artery graft failures still occur due to diffuse narrowing, known as the string phenomenon. Studies suggest that the string phenomenon is caused by competitive flow when the coronary stenosis is not serious, but the hemodynamics of the string phenomenon are still unclear. The purpose of this study is to clarify the hemodynamic characteristics of the string phenomenon.
A patient-specific 3-dimensional model of the aortic arch and coronary arteries was reconstructed. A moderate stenosis was applied to the left anterior descending artery. The internal thoracic artery was used to bypass the stenosis. Two further 3D models were built to study the hemodynamics of the string phenomenon.
A numerical study was performed by coupling the 3D artery model with 0-dimensional lumped parameter model of the cardiovascular system.
The graft flow, native coronary flow, wall shear stress and oscillatory shear index were calculated and illustrated. Inverse flow and high oscillatory shear index appeared on the internal thoracic artery graft when the stenosis was moderate.
High oscillatory shear index might be the major hemodynamic characteristic of the string phenomenon in internal thoracic artery graft. The inverse graft flow and the difference in graft flow caused by clamping the stenosis can be used to evaluate the probability of observing the string phenomenon.

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Original articleAdult cardiacIncreased Graft Occlusion or String Sign in Composite Arterial Grafting for Mildly Stenosed Target Vessels

Background

Methods

Results

Conclusions

Section snippets

Study Design

Results

Comparison of Composite and Individual Grafting

J Thorac Cardiovasc Surg

Ann Thorac Surg

Ann Thorac Surg

Ann Thorac Surg

Ann Thorac Surg

Original article
Adult cardiac
Increased Graft Occlusion or String Sign in Composite Arterial Grafting for Mildly Stenosed Target Vessels